Method of fabricating a display device

ABSTRACT

An object of the technology of our invention is to solve a luminance defect viewed as a &#34;seam&#34; or the like and to provide a liquid crystal display device having a screen for equally displaying an image. For example, when an exposing process is performed for one conductor layer or a dielectric layer, a total of four photomasks are used corresponding to four shot areas. A light insulation layer of a photomask used for the exposing process for patterning for example a signal line is formed so that it becomes a projection pattern of the signal line. The photomasks corresponding to adjacent shot areas are formed so that patterns of the light insulation layers of the boundary portion are engaged with each other on the plane.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a liquid crystal display device and afabrication method thereof, in particular, to a liquid crystal displaydevice having a screen for equally displaying an image free of a lineshaped luminance defect and a fabrication method thereof.

BACKGROUND OF THE INVENTION

A related art reference of the present invention will be described withreference to an active matrix type liquid crystal display device havinga display pixel electrode array that is constructed of thin filmtransistors (thereinafter referred to as TFTs) as switching devices.

The active matrix type liquid crystal display device comprises an arraysubstrate, an opposite substrate, and a liquid crystal material. Adisplay pixel electrode array is formed on the array substrate. Anopposite electrode is formed on the opposite substrate. The liquidcrystal material is disposed between the array substrate and theopposite substrate. The TFTs and display pixel electrodes connectedthereto are formed on the array substrate in a matrix shape. Inaddition, scanning lines are connected in common to gates of the TFTs inthe column direction of the matrix. Signals lines are connected incommon to drain electrodes of the TFTs in the row direction of thematrix. Moreover, capacitive lines and so forth are disposed opposite tothe display pixel electrodes through an insulation layer.

These electrodes and semiconductor devices such as TFTs areconventionally fabricated by thin film pattern forming technologies,namely photofabrication technologies.

In a conventional thin film pattern forming process, a thin filmmaterial is formed on a substrate by a particular film forming methodsuch as spattering method or CVD method. The thin film is patterned in adesired shape by so-called photoetching process (PEP).

In other words, a photoresist is coated on the thin film formed on thesubstrate. The photoresist is developed in a predetermined pattern by anexposing process. In other words, a photomask having a light insulatingmember with a predetermined pattern is aligned on the upper surface ofthe substrate. Rays of light are exposed to the substrate through thephotomask.

Thereafter, the exposed photoresist is developed. With a mask of thedeveloped photoresist, the undesired portion of the thin film formed onthe substrate is etched out and a desired pattern is obtained. Byrepeating these processes the number of times corresponding to thenumber of layers of thin films that construct the electrodes andsemiconductor devices, a desired device can be fabricated.

As the areas of optical devices such as liquid crystal display devicesincrease, needs of thin film forming technologies and patterningtechnologies for fabricating their display devices are becoming strong.

For example, when the exposing process is performed, since an opticalportion of the exposing device has a restricted performance, the area ofthe substrate that is exposed by the exposing device at a time isrestricted. To expose a large area of a substrate, so-called divisionexposing (stepper) method is employed.

In the division exposing method using the stepper, the area of thesubstrate to be exposed is divided into a plurality of exposure areas asshown in FIG. 11. The exposing device performs the exposing process(shot) for one of the divided exposure areas at a time. Thus, theexposing process is repeated the number of times corresponding to thenumber of the divided areas (namely, the process is performed inso-called step and repeat method). As a result, the exposure process isperformed on the entire surface of the substrate. Consequently, theexposing device can expose a large area of a substrate that is greaterthan the area of the exposing device.

However, in an active matrix type liquid crystal display apparatusfabricated by the stepper method, when the same image signal is input topixels in different exposure areas, the luminances thereof may bedifferent from each other. In particular, when the difference ofluminances in adjacent exposure areas is large, the boundary line ofeach exposure area is viewed as a "seam". Thus, the display quality ofthe active matrix type liquid crystal display apparatus that shoulddisplay an image with high accuracy is remarkably deteriorated.

It is known that the difference of luminances in adjacent exposure areasresults from the following reasons.

In other words, in a capacitive drive type display device such as aliquid crystal display device, a divided voltage of the input signaltakes place between the capacitance of the pixel and a stray capacitanceof the pixel. Thus, the voltage applied to the pixel is shifted by thedivided voltage of the stray capacitance.

The amount of the stray capacitance depends on the overlap amount ofeach thin film pattern that constructs each pixel of the display device.When a photomask used for the exposing process of each thin film layeris aligned with an error against a predetermined position, a developedphotoresist pattern and an etched thin film pattern deviate from theirpredetermined positions. Thus, the upper thin film pattern deviates fromthe lower thin film pattern. Consequently, the overlap amount of thefabricated device deviates from the designed overlap amount.

In addition, due to the accuracy of the drive portion of the exposingdevice, the deviation of a photomask in one exposure area (namely, maskalignment) may be different from that in another exposure area.Consequently, since the overlap amount and the stray capacitance in oneexposure area are different from those in another exposure area, thevoltage shift amount varies in each exposure area.

Thus, in the liquid crystal display device fabricated by theconventional fabrication method, there is a difference of luminances indifferent exposure areas, resulting in an irregular display image.

Experimental results of the display screen of the liquid crystal displaydevice fabricated by the conventional fabrication method shows thefollowing points. In particular, when the same image signal is input topixels in two adjacent exposure areas, if the difference oftransmittances of pixels in one area and pixels in another area is 0.5%or greater, the difference is viewed as a "seam" of the areas.

The present invention is made from the above-described point of view. Anobject of the present invention is to provide a liquid crystal displaydevice having an equal display screen free of an obtrusive line-shapedluminance defect such as a "seam".

SUMMARY OF THE INVENTION

In the case that a photoresist is exposed with a plurality of areas fora display device such as a liquid crystal display device and then pixelsare patterned in an array shape, if there is a difference of luminancesin the divided display areas (small areas), the graduation of change ofluminances in the vicinity of the boundary line of adjacent areas isdecreased so as to allow the "seam" of the areas to be unobtrusive. Thisis the fundamental technical art of the present invention.

In other words, according to the display device and the fabricationmethod of the present invention, the boundary line of small areas isformed so that pixels of adjacent display areas are mixed in a boundaryarea thereof so as to equalize the apparent difference of luminances ofpixels in the vicinity of the boundary line of the small areas.

Thus, according to the related art reference, since display areas aredivided by a straight line along a boundary line, the difference ofluminances of left and right display areas or upper and lower displayareas is large. Consequently, the difference of luminances on theboundary line is remarkably viewed. However, according to the presentinvention, since the curve of change of luminances from one display areato another display area is gradual, the difference of luminances on theboundary line of the display areas is almost unobtrusive.

In addition, according to the fabrication method of the display deviceof the present invention, a thin film that constructs a display deviceis divided into small areas and a photoresist is exposed or a thin filmis patterned so that the boundary line of adjacent small areas is formedin a non-linear shape. Thus, pixels in one patterning area and pixels inanother patterning area are mixed in the vicinity of the boundary lineof the adjacent areas. Consequently, even if the luminancecharacteristics of pixels in both areas deviate due to the misalignmentof masks in the patterning process, the apparent luminances in thevicinity of the boundary line can be equalized.

Thus, the change of luminances in adjacent exposure areas due to theshot deviation in for example the division exposing process can bedecreased and the boundary line of the areas can become unobtrusive.

Examples of the conductor layer or dielectric layer according to thepresent invention are metal layers of Cr, Al, and the like,semiconductor layers such as amorphous silicon film, doped layers inwhich impurities are doped in the semiconductor layers, and insulationfilm layers such as SiOx film and SiNx film.

The area in the vicinity of the boundary line is an area includingpixels disposed on the boundary line of at least adjacent areas. Thewidth of the area on the boundary line varies depending on parameterssuch as luminance characteristics of each display device. However, thewidth of the area on the boundary line should be designated so that theapparent difference of luminances on the boundary line is unobtrusive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an outlined structure of a pixel of aliquid crystal display apparatus fabricated according to an embodimentof the present invention;

FIG. 2 is a sectional view showing the structure taken along line 2--2of FIG. 1;

FIG. 3 is a plan view conceptually showing a process for dividing anarea of a thin film formed on an array substrate of the liquid crystaldisplay apparatus according to the present invention into a plurality ofshot areas and performing an exposing process for each of the dividedareas;

FIG. 4 is an enlarged view partially showing the vicinity of a boundaryline of the adjacent shot areas (small areas) of FIG. 3;

FIG. 5 is an enlarged view partially showing a pixel array of the liquidcrystal display device fabricated by applying the small area dividingmethod according to the present invention to a real pixel pattern;

FIG. 6 is a plan view showing outer shapes of mask patterns ofphotomasks used in a fabrication method according to an embodiment ofthe present invention;

FIG. 7 is a schematic diagram showing a pattern with a center narrowportion formed in a double exposure area;

FIG. 8 is a graph showing a logical curve of applied voltages (signalline voltages) and transmittances of the active matrix type liquidcrystal display device according to the embodiment;

FIG. 9 is a plan view showing an arrangement of pixels constructing aboundary line at random pitches according to the present invention;

FIG. 10 is a plan view showing a boundary line that traverses a pixel aplurality of times; and

FIG. 11 is a plan view showing a patterning process for a dividedexposing type display device fabricated using a conventional stepper.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the accompanying drawings, an embodiment of thepresent invention will be described below. In this embodiment, thepresent invention is applied for an active matrix type liquid crystaldisplay apparatus. FIG. 1 is a plan view showing an outlined structureof a pixel of an array substrate fabricated corresponding to afabrication method according to the present invention. FIG. 2 is asectional view taken along line 2--2 of FIG. 1.

A plurality of TFTs 52 and a plurality of display pixel electrodes 9connected thereto are disposed in a matrix shape on an array substrate.The TFTs 52 are connected to scanning lines 50 in a row direction of thearray substrate. In addition, the TFTs 52 are connected to signal lines51 in a column direction of the array substrate.

Each TFT 52 comprises a gate electrode 2 integrally formed with ascanning line 50, a gate insulation film 4 formed on the gate electrode2, a source electrode 7, and a drain electrode 8 disposed opposite tothe source electrode 7 through a semiconductor layer 5.

The source electrode 7 is connected to the display pixel electrode 9.The drain electrode 8 is integrally formed with the signal line 51.Ohmic contact layers 6 are disposed between the source electrode 7 andthe semiconductor layer 8 and between the drain electrode 8 and thesemiconductor layer 8.

When necessary, a capacitive electrode 3 is formed below the displaypixel electrode 9 through the gate insulation film 4 in such a mannerthat the capacitive electrode 3 is disposed opposite to the displaypixel electrode 9. A capacitor is formed by the capacitive electrode 3,the display pixel electrode 9 opposite thereto, and the gate insulationfilm 4 surrounded by the capacitive electrode 3 and the display pixelelectrode 9.

Next, the fabrication process of the array substrate according to thepresent invention will be described.

A Ta film is deposited on an electrically insulating substrate 1 withlight transmitting characteristics by spattering method. An example ofthe substrate 1 is a glass substrate. Thereafter, the front surface ofthe resultant structure is patterned in a desired shape by PEP method soas to form connection terminals (not shown) connected to the scanninglines 50 in the row direction of the substrate 1 and an externalcircuit.

Thereafter, an SiOx film, an a-Si film, and a n+ a-Si film aresuccessively deposited on the resultant structure by CVD method. Next,the a-Si film and the n+ a-Si film are patterned in a desired shape byPEP method. As a result, the semiconductor layer 5 and the ohmic contactlayer 6 are formed.

Thereafter, an indium tin oxide (ITO) film is deposited on the resultantstructure by spattering method and then patterned in the shape of thedisplay pixel electrode 9 by PEP method.

Next, an Al film is deposited on the resultant structure by spatteringmethod and then the source electrode 7, the drain electrode 8, and thesignal line 51. The signal line 51 is integrally formed with the drainelectrode 8.

The PEP process for forming each electrode layer and the semiconductorlayer comprises a process for forming a thin film of a material to bepatterned, a process for coating a photoresist on the entire surface ofthe thin film, a process for exposing the photoresist with a photomaskon which a predetermined pattern is drawn, a process for developing theexposed photoresist and obtaining a predetermined pattern (resistimage), and process for etching out the undesired portion of the thinfilm with a mask of the photoresist by a photoetching patterning methodsuch as wet etching method or chemical dry etching method.

In the exposing process, the thin film forming area on the arraysubstrate is divided into a plurality of shot areas. The exposingprocess is performed for each of the divided shot areas. FIG. 3 is asectional view conceptually showing the divided shot areas. As shown inFIG. 3, the area on the substrate is divided into four shot areas a, b,c, and d. The exposing process is performed for each of the shot areasa, b, c, and d. This method is referred to as division exposing method.

FIG. 4 is an schematic diagram for explaining the division exposingmethod in detail. FIG. 4 is an enlarged view showing the vicinity of aboundary line 301 of adjacent shot areas represented by a dotted line inFIG. 3. In FIG. 4, each dot represents an area on which one pixel isformed. Black dots 401 represent pixels in one shot area. On the otherhand, white dots 402 represent pixels in another shot area. In otherwords, the pixels represented by the black dots 401 belong to the rightside small area of FIG. 4. On the other hand, the pixels represented bythe white dos 402 belong to the left side small area of FIG. 4.

As shown in FIG. 4, the boundary line 301 of the areas is formedcorresponding to the arrangement in the vertical direction of the pixelsso that pixels of the different shot areas are regularly mixed atpitches of three pixels in the row direction and six pixels in thecolumn direction. In other words, the boundary line 301 that is acontour line of each small area is formed in a non-linear shape.

FIG. 5 is an enlarged plan view showing a part of a pixel array of theliquid crystal display device fabricated by applying the small areadividing method for a real pixel pattern. In FIG. 5, a dotted line 501represents a boundary line of adjacent shot areas (namely, the boundaryline 301 of FIG. 3). A contour line of a photomask is patterned so as toperform the exposing process corresponding to the pattern represented bythe dotted line.

FIG. 6 is a plan view showing photomasks. As shown in FIG. 6, in thisembodiment, a total of four photomasks 60 are used for exposing oneconductor layer or one dielectric layer corresponding to four shot areasa, b, c, and d. Each of the photomasks 60 is fabricated by forming alight insulation layer 62 composed of Cr or the like on a transparentsubstrate 61 composed of glass, artificial quartz, or the like in apredetermined pattern. For example, the light insulation layer 62 forthe photomasks used for patterning the signal lines 51 is formed as aprojection pattern of the signal lines 51. The photomasks (for example,the masks a and b) corresponding to the adjacent shot areas are formedin such a manner that the patterns of the light insulation layers 62 inthe boundary portion are alternatively engaged with each other on theplane.

The four shot areas are exposed corresponding to the four photomasks a,b, c, and d by the division exposing method. Thereafter, a thin film ispatterned by the etching process.

The exposing process and the etching process are performed for each thinfilm that constructs the array substrate. As a result, the arraysubstrate as shown in FIGS. 1 and 5 is obtained.

In this embodiment, a so-called overlapped exposing process is performedin the vicinity of the boundary of the shot areas.

In the overlapped exposing process, each shot area is exposed in such amanner that it is partially overlapped with a part of another adjacentshot area that has been exposed. The overlapped exposing process isperformed so as to prevent a portion in the vicinity of a boundary lineof shot areas from being unexposed.

Actually, the positions of the photomasks are aligned so that the edgeportions of areas that have been exposed are exposed. For example, eachphotomask is aligned so that the boundary line represented by the dottedline shown in FIG. 3 becomes a dual line with a predetermined width.

In addition, the exposure amount of the photoresist in the area on whichthe overlapped exposing process is performed is greater than theexposure amount of the other areas. Thus, when the area on which theoverlapped exposing process is performed is developed, the pattern widthof the photoresist may be narrow. Consequently, the thin film patternedwith such a mask may be formed in a shape with a center narrow portionsuch as a wiring pattern 702 of a overlapped exposure area 701 as shownin FIG. 7.

Since the pattern shape (pattern width) of pixels formed in theoverlapped exposure area may be different from that in other areas, itis not preferable to excessively widen the overlapped exposure area forobtaining equal display characteristics.

Thus, in this embodiment, the overlapped exposing process is performedat a pitch of one pixel. In reality, the width of the overlappedexposure area is preferably 10 μm or less. In this embodiment, the widthof the overlapped exposure area is 6 μm. Experimental results show thatirregular luminance does not take place in the overlapped exposure areaand thereby an image can be properly displayed. In other words, theoverlap width of the overlapped exposure area should be predeterminedcorresponding to the characteristics of the liquid crystal displaydevice so that the narrow portion of the pattern does not adverselyaffect the image quality.

The array substrate fabricated by the above-described fabrication methodis disposed opposite to the opposite substrate 21 as shown in FIG. 2.The gap between the array substrate and the opposite substrate 21 isfilled with a liquid crystal material. As a result, an active matrixtype liquid crystal display device is obtained. As shown in FIG. 2, anopposite electrode 22 composed of a transparent electrode material isformed on the entire inner surface of the opposite substrate 21. Inaddition, when necessary, alignment films (not shown) are formed betweenthe array substrate 20 and the liquid crystal and between the oppositesubstrate 21 and the liquid crystal. Moreover, a light insulation layermay be formed in an area opposite to the gap of the display pixelelectrode of the opposite substrate 22. Furthermore, a color filterlayer of R, G, and B may be formed in an area opposite to the displaypixel electrode.

The display quality of the liquid crystal display device according tothe present invention was evaluated in the following manner.

First, the luminance of each of a plurality of points on the displayscreen was measured so as to obtain the difference of luminances in shotareas.

In other words, the same image signal was input to the signal lines 51.With a luminance meter, the luminances at a plurality of positions ofeach shot area were measured. The mean values were compared with eachother as representative values of the luminances in the shot areas.

FIG. 8 is a graph showing a logical curve of applied voltages (signalline voltages) and transmittances (namely, V-T curve) of the activematrix type liquid crystal display device according to this embodiment.In FIG. 8, a signal line voltage represents a voltage that is input to asignal line. A transmittance represents a relative value of a luminanceassuming that the luminance at a signal line voltage of 0 V is 100%. Inthe evaluation method of this embodiment, a voltage of approximately 2.5V was applied to a signal line 51 so that the transmittance of eachpixel logically becomes 50%.

Measurement results show that the difference of transmittances indifferent shot areas is 0.6%.

Next, the active matrix type liquid crystal display device according tothis embodiment was sensuously tested to determine whether or not toview a boundary line of shot areas. In reality, the display deviceaccording to this embodiment was disposed in a darkroom. A screen wasdisplayed in the same drive condition as the above-described luminancemeasurement test and a total of 100 people conducted the sensuous testso as to determine whether or not to view the boundary line.

As the results, these test attendants could not view the boundary line.In addition, with different viewing angles, the same tests wereconducted. As the results, these test attendants could not view theboundary line of shot areas.

Moreover, an active matrix type liquid crystal display device that wasfabricated in the same manner as the above-described embodiment and thathas different pitches of pixels was tested in the same manner. In thistest, the difference of transmittances of adjacent shot areas was only1.0%. However, the boundary line of shot areas was not viewed at all.

Thus, according to the display device of the present invention, since aboundary line of adjacent shot areas is not viewed at all, an image canbe displayed with high quality. In addition, according to thefabrication method of the display device of the present invention, evenif there is difference of luminances of pixels in adjacent shot areas(small areas) due to the deviation of mask alignment in thephotofabrication process, the difference of luminances that is aboundary line can be ignored. As a result, the yield of fabrication canbe remarkably improved.

The fabrication method of the present invention can be applied for thecase that the number of shots is greater than that of theabove-described embodiment. Thus, the area of the display device can befurther increased.

It should be noted that the present invention is not limited to theabove-described embodiment. Instead, various modifications areavailable. For example, as the patterning method, a method other thanthe so-called PEP method can be used. In addition, the structure of theTFT device is not limited to the above-described structure. For example,a channel protection film composed of an insulating material such asSiOx may be formed on a semiconductor layer in a channel area of a TFT.In this case, the fabrication method of the present invention can beapplied for the patterning process of the channel protection film.

Moreover, the sequence of forming processes of each electrode layer anddielectric layer is not limited to that of the above-describedembodiment. When necessary, the laminating order of layers may bechanged. Alternatively, when the patterning process is performed, aplurality of layers may be exposed and etched at a time.

Furthermore, the matrix arrangement of pixels may be changed to anyarrangement other than the row and column matrix.

In the above-described embodiment, the shot area dividing method ofwhich pixels of one shot area and pixels of another shot area areregularly mixed on the boundary of these shot areas. However, it shouldbe noted that the dividing method is not limited to such a method.Instead, various modifications are available.

When the width of mixed pixels of both shot areas (namely, the pitchesin the column direction) is 0.5 cm or greater, more preferably 1 cm orgreater, the rate of change of luminances remarkably decreases. Even ifthe difference of luminances of adjacent areas is 1% or greater, theboundary line could become unobtrusive.

The pitches in the column direction are not always regular. For example,as shown in FIG. 9, the pitches of pixels that construct a boundary linemay be arranged at random. In reality, the pitches of mixed pixels inadjacent areas are designated so that they vary at random (with randomnumbers) corresponding to the width of each pixel (namely, the pitch ofeach pixel in the column direction). The pitch of pixels in adjacentareas at each row position is designated by multiplying the pitch ofeach pixel by a random number. In this embodiment, the width of eachpixel is 100 μm. In addition, random numbers vary in the range from 0 to99. Thus, the maximum pitch is 0.9 cm. The pitches of individual columnsvary in such a range at random.

Experimental results show that randomly designated pitches areespecially effective for a color liquid crystal display apparatus ofwhich a color filter is used for a liquid crystal display device.

In other words, depending on a designating method of a boundary line, aboundary line may pass through pixels of one particular color of threeprimary colors R, G, and B. In this case, the luminance of each pixel onthe boundary line is almost the mean value of the luminances ofparticular color components between one shot area and another shot area.However, since the colors R, G, and B have different luminousities, theluminance of each pixel on the boundary line may remarkably deviate fromthe mean value of luminances of left and right shot areas of which R, G,and B components are composited. Thus, depending on the difference ofluminances of adjacent shot areas, a portion with a large luminancedifference may be viewed as a boundary line.

On the other hand, when the pitches of pixels in the column direction ofthe boundary line are randomly designated, the probability of which theboundary line passes through only particular color pixels can becomealmost zero. Thus, the luminance of pixels on the boundary line isalmost the mean value of the luminances of left and right shot areas ofwhich R, G, and B components are composited. Consequently, the luminanceof one shot area does not have a large difference from that of anothershot area. In such a manner, the probability of which a boundary line isviewed can be further effectively reduced.

In addition, as shown in FIG. 10, a boundary line may traverse one pixelseveral times. In the method shown in FIG. 10, the boundary line isdesignated so that one pixel is divided into three portions. Thus, therate of change of luminances can be further reduced.

Now, assume the case that the distance between a display pixel electrode9 and a signal line 51 in a portion of an upper exposure area a deviatesfrom that in a portion of a lower exposure area b due to the dislocationof a photomask in the exposing process. Thus, the stray capacitancebetween the display pixel electrode 9 and the signal line 51 in theexposure area a is different from that in the exposure area b. Thedifference of stray capacitances causes the voltage applied to theliquid crystal in the area a to be different from that in the area b. Inthe method as shown in FIG. 10, since there are two distances betweenthe display pixel electrode 9 and the signal line 51, the resultantstray capacitance becomes the mean value between the stray capacitanceof the exposure area a and the stray capacitance of the exposure area b.Thus, the rate of change of voltages becomes the means value of theseareas. Consequently, when such pixels are disposed between two areas,the rate of change of luminances can be reduced.

In this embodiment, the boundary line of shot areas on each layer (thinfilm) that is patterned passes through the same pixel area. In otherwords, if the boundary line passes through different pixels on theindividual thin film layers, the stray capacitance varies on each thinfilm. Thus, it is very difficult to predict the change of luminances inthe vicinity of the area of the boundary line due to the change of straycapacitances. On the other hand, when the boundary line of each layerpasses through the same pixel area, since the luminances of left andright shot areas are averaged, the luminance distribution can be easilypredicted (namely, designated). Thus, the effects of the presentinvention of which a boundary line becomes unobtrusive can be moreeasily and securely performed.

In addition, according to the present invention, the above-describedmethods can be used in combinations. For example, a part of a boundaryline may have random pitches. Alternatively, by the repetition of aboundary line of a portion with random pitches, one boundary line may beformed. With a proper combination of a plurality of factors of methods,an optimal method can be selected.

Thus, according to the active matrix type liquid crystal display deviceof the above-described embodiment, since a boundary line of adjacentareas (adjacent small areas) that have been divided in an exposingprocess becomes unobtrusive, a screen with a high display quality can beaccomplished. In addition, according to the fabrication method of theactive matrix type liquid crystal display device of the above-describedembodiment, even if there is a difference of luminances in exposureareas, a boundary line of these areas can become unobtrusive. Thus, theyield of the fabrication can be improved.

Industrial Utilization:

As described above, according to the present invention, a boundary lineof adjacent areas with different transmittances can become unobtrusive.In addition, according to the fabrication method of the thin filmfabricating process, the yield of each structural portions of the arraysubstrate can be remarkably improved.

We claim:
 1. A method for fabricating a display device, comprising thesteps of:making a stacked layer of a conductor layer and a dielectriclayer on a plurality of small areas of an insulation substrate; andpatterning the conductor layer or the dielectric layer of each smallarea so as to make pixels in a predetermined arrangement, wherein aboundary line of adjacent small areas is formed in a non-linear shape.2. A method for fabricating a display device, comprising the stepsof:making a stacked layer of a first thin film and a second thin film ona plurality of small areas of an insulation substrate, the first andsecond thin films being composed of a conductor layer or a dielectriclayer; and patterning the first and second layer of each small area soas to make pixels in a predetermined arrangement, wherein each of aboundary line of adjacent small areas on the first thin film and aboundary line of adjacent small areas on the second thin film are formedin a non-linear shape, the boundary line on the first thin film and theboundary line on the second thin film passing through the same pixelarea.
 3. The method as set forth in claim 1,wherein the display deviceis a liquid crystal display.
 4. The method as set forth in claim1,wherein said patterning step is performed by light radiating means. 5.A method for fabricating a display device, comprising the stepsof:making a stacked layer of a conductor layer and a dielectric layer ona plurality of small areas of an insulation substrate; and patterningthe conductor layer or the dielectric layer of each small area so as tomake pixels in a predetermined arrangement, wherein the boundary line ofadjacent small areas traverses any pixel several times.